1. Field of the Invention
This invention relates to screen doors and sashes, and more particularly to a middle rail assembly for centrally clamping a screen within a frame structure of such door and sash.
2. Prior Art
In prior-art screen doors or sashes, there were used woven mesh screens made of metal or plastic wires, or textile material, such screens being retained in place usually by rubber gaskets disposed along the inner periphery of a frame structure by upper and lower rails and a pair of spaced-apart vertical stiles. The screen was further held taut at a middle rail of the frame structure by similar gaskets in order to prevent the entrance of litter and insects into the building interior, which would occur if the screen were slack and thus leaky. The marginal edges of the screen were held in a groove in the middle rail by rubber gaskets, thereby permitting the screen to be clamped peripherally within the frame structure. The operation of stretching or tensioning the screen on the middle rail by such rubber gaskets was time consuming and tedious. As the rubber gaskets were exposed on the surface of the middle rail, the screen sash or door as a whole appeared unsightly. Screen doors or sashes as used with such middle rail construction were not compatible with a single-expanse screen but only with a two-piece screen, one of the latter being clamped between the top rail and the middle rail, and the other disposed between the middle rail and the bottom rail.